Resistors info again

[hmm]

I have a degree in physics, but it was a specialised physics, not a general run of the mill degree - nearly killed me too.

No excuse really, in truth I have just forgotten an awful lot...

But what is the difference between a:

220 Ohm Resistor
and a 3.9K resistor, for example.

It is the nomenclature that is getting to me.

And if I am looking for this 220 Ohm resisistor on the rapid site, here:
http://www.rapidonline.com/productinfo.a...&added=true

what would the 220 Ohm resistor be advertised as?

Thanks

 

[DAVIDO]

Our in house boffin reckons 3k3 is 3300ohms. We have thousands of different resistors here pm me when you find out exactly what you want. If we have something to suit ill bung them in an envelope for you.

 

[hmm]

Thanks, that'll mean 220 ohms is 0.22K ohms - I don't know why this recipe book I'm following is so hard to read.

Could have something to do with the reader.

Thanks for the offer, but there is a whole bunch of other stuff I need to order - Rapid do some good woodworking tools too)

 

[stevebirch2002]

Resistors usually have 2 or 3 different values.

1. Resistance in Ohms
2. Power handling capability in Watts
3. Resistance variance in Percentage.

Resistance values are in preferred values. e.g. 47 ohms, 56 ohms, 68 ohm and muliplies thereof (470 ohms, 560 ohms, 680 ohms, 4.7 kohms, 5.6 kohms, 6.8 kohms etc etc)

The resistance values can be read from a colour banding system that can be remembered from the old nmeumonic
Black (Black 0), Bas***ds (Brown 1) Rape (Red 2) Our (Orange 3) Young (Yellow 4) Girls (Green 5) But (Blue 6) Virgins (Violet 7) Grow (Grey 8) Wise (White 9)

Therefore a 22 ohm would be Red Red Black
220 ohm would be Red Red Brown
2.2 kohm (2200) = Red Red Red
47 kohm = (47000) = Yellow Violet Orange

If there are four bands then the fourth is usually a percentage variance.

Sorry about the unPC mneumonic but that is what I was taught in the early 1970s

 

[cliff]

This might be of some help /forums/images/graemlins/grin.gif
--------------------

"Artificial intelligence is no match for natural stupidity"
sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>

 

[st599]

Decimal points aren't used in schematics, as they can get misunderstood after photocopying etc. So a 4.7 kilohm resistor would be marked as 4k7 etc.

 

[cpedw]

I see from your link that Rapid sell zero ohm resistors - only 50 p for a pack of 100, order code 62-0314.
In case you're still puzzling, the 220 ohm resistors are described as 220R, code 62-0354.

Derek

 

[Como]

For small quantities of all the components it might be worth visiting your local Maplins or looking on thier web site as I think they do smaller quantities than the 100. In general the K (1000), R (1) or M (1000000) replaces the decimal point in the value so your 3.9K would be shown as 3K9 and you 200 ohm as 220R.

 

[AliM]

I learnt:
Black bas***ds raping our young girls, british virgins getting worried.

No less un-PC, but I've remembered it for 30 years, so it obviously had the desired effect!

 

[cliff]

[ QUOTE ]
I learnt:
Black bas***ds raping our young girls, british virgins getting worried.

No less un-PC, but I've remembered it for 30 years, so it obviously had the desired effect!

[/ QUOTE ]Bad Boys Rape Our Young Girls But Violet Goes Willingly /forums/images/graemlins/grin.gif
--------------------

"Artificial intelligence is no match for natural stupidity"
sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>

 

[andy01842]

I learnt
black boys rape our young girls but virgins go without

 

[stevebirch2002]

Where are all these Virgins.......?

 

[Sixpence]

They went without , keep up old chap

 

[srp]

Just to make life complicated, some resistors have 4 colour bands to denote their value, rather than 3 (there is also an extra band which denotes the tolerance, on its own at the other end).
The best help I can give is to suggest you download this program - it's 2.4mB and not only allows you to work out resistor colour codes and values, it also sorts out capacitors, does calculations for you, works out resistor values when using led's and loads more. And it's free. We use it quite a bit at work.

 

[Sixpence]

Very useful little download , many thanks

 

[hmm]

Thank you

Thank you, Thank you.

Great advice, links and info.

Cheers.

I'm toying around with a few little projects, one of them is an IR imaging device - more for fun, to see if I can, rather than to obtain the actual item, but if I can make one and learn a bit, all well and good. (I'm working up to this one - starting with a few easier ones, and I may be able to lay my hands on a pcb cutting machine (well it cuts copper board- to save me a bit of effort - and to play with too)

 

[john_morris_uk]

[ QUOTE ]
Resistors usually have 2 or 3 different values.

1. Resistance in Ohms
2. Power handling capability in Watts
3. Resistance variance in Percentage.



[/ QUOTE ] You forgot that some very high value resistors also have a voltage rating! The resistor may be quite capable of dissipating the fractions of a Watt that heats it throught the micor or miili amps that flows through it from the very high voltage, but it arcs over as its too small physically.

Strange but true rating for some high value resistors!!

OK so you said 'usually' have ratings. I am quoting the unusual.

 

[stephenmartin]

Keep your racist remarks to yourself....Some people do take offence....Being black I prefer

Bye (Blk) Bye (Brwn) Rosie (Red) On (Orange) You (Yellow) Go (Green) to Birmingham (Blue) Via (Violet) the Great (Grey) Western (White)

You can even teach children this one